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Subject: Re: Assymetry & Bonus in Static Eval? Black apples and white pears?

Author: Vincent Diepeveen

Date: 16:50:15 12/05/99

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On December 04, 1999 at 22:09:41, Eelco de Groot wrote:

>Steve:
>Do I understand correctly--for each static evaluation of a single position (leaf
>node, I guess), the program evaluates based on material and positional factors
>without regard to which side is on the move?  Then, some programmers like to add
>a bonus for the side to move?
>
>Vincent:
>It's an heuristic that's true in 99% of the positions that my program
>searches obviously.
>
>If a position is bad then usual programs nullmove. If a program nullmoves
>then the other side has the move so gets the bonus.
>
>So the sword cuts on 2 sides. Where you can nullmove normally to prevent
>getting into a worse position, you now suddenly cannot as your opponent
>gets the bonus instead of you.
>
>
>Me:
>Now I have never done any chessprogramming, but it seems fairly straightforward
>to say that you only need to think about such a bonus if you are comparing
>positions with White to move and positions with Black to move, right?
>Intuitively something tells me that is not without dangers. Isn't that a lot
>like comparing apples and pears? Wouldn't it be a lot better if only even plies
>were evaluated if possible? A recent discussion between Ed and Christophe about
>the early Rebel comes to mind... That way you can focus much more on plans ,
>weaknesses, etc. of your own. You could save a lot of time time that way! Of
>course you can't ignore the opponent regardless, but you could use a different
>evaluation for uneven plies, looking more for tactical threats for instance?
>That would be relatively safe to do as long as you have the initiative..
>
>If this isn't possible because of nullmove, isn't that a weakness of normal
>nullmove? Vincent I understand you are working on something you call double
>nullmove and that you are going to publish in ICCA journal about it. Has this
>anything to do with these even/uneven effects. Has double nullmove replaced the
>bonus in Diep? I must confess nullmove is hardly my expertise, but maybe others
>can follow better if you have anything to say about this.
>
>Thanks for any comments, by anybody

Having a passed pawn can be seen as a risky bonus too.
It might be hung!

>Eelco



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